Ba₂YCu₃O_x was prepared by the vacuum calcination and subsequent oxidation of Ba₂YCu₃O_x prepared by a conventional ceramic method. Surface state of this sample was examined by the X-ray photoelectron spectroscopy. During the vacuum calcination up to 1200 K. two temperature maxima in the deoxidation rate were observed at around 670 K and 1170 K. First peak was correspond to the orthorhombic to tetragonal phase transition in Ba₂YCu₃O_x and second peak came from the reduction of Cu²⁺ to Cu¹⁺ accompanied by the decomposition of Ba₂YCu₃O_x. This sample was easely oxidized in oxygen atmosphere at around 1173 K. After the vacuum calcination and subsequent oxidation, the surface condensation of Ba and Y usually observed in Ba₂YCu₃O_x prepared by the conventional ceramic method was eliminated. This came from the evolution of CO₂ from carbonate ion remained at the surface layer of Ba₂YCu₃O_x occurred during the vacuum calcination.